Problems for
Intermediate Methods in Theoretical Physics

Edward F. Redish

The Dirac Delta Function

In lecture, we introduced the Dirac delta function in order to be able to write

.

We defined the delta function as

.

(a) Use the definitions to argue the following properties of the delta function:

(b) For some applications we will have to use the delta function of a function of x rather than just of x itself. (For example when we want to integrate over momentum states -- p -- but want to conserve energy -- E = p2/2m.) Show that:

.

where the set of xi are the solutions (there may be more than one) of the equation

g(x) = 0.


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This page prepared by

Edward F. Redish
Department of Physics
University of Maryland
College Park, MD 20742
Phone: (301) 405-6120
Email: redish@umd.edu

Last revision 13. November, 2005.